A Certain RTS Spinoff Game's Units as Monsters
Stats for WWN but hopefully easily usable in other B/X derivations.
Anubite
With the body of a human but the head and feet of a dog, these 9' tall beast-men are the spawn of ancient sorcery gone awry. They reproduce by eating corpses, specifically the hearts of unworthy ones. Ancient magic prevents them from harming wizards directly, though stripping them of their gear and leaving them to wander the steppe remains possible.
When entering combat, the Anubite may make a leap up to 30' as an on-turn action. On the turn they make this leap, they gain a +2 bonus to damage and to-hit rolls.
HD:2 AC:14 Atk:+2 Dmg:1d6+3 Shk:3/15 Mv:30' ML:9 Skl:+1 Save:14+
Wadjet
A giant snake, around 10' long, with small wings on its hood. The wings don't enable it to fly, serving only to allow the snake to hold itself vertically. The Wadjet tends to hunt by hiding flat behind a dune or hill, throwing itself vertical to spit poison at its enemies, and retreating before they have time to react, only later returning to feast on their kill.
A target hit by the poisonous spit of a Wadjet must make a Physical save. On a failure they take 1d4 poison damage per round for 2d4 rounds.
HD:3 AC:15 Atk:+4 Dmg:1d4 Shk:1/13 Mv:35' ML:8 Skl:+2 Save:12+
The Golden Boar
The Golden Boar's runes still function near-perfectly after all this time. Unfortunately, they cause it to attack any non-Dwarf not carrying the seal of the high-king. If disabled, the raw gold in the boar is worth at least 10,000sp.
Any human-sized target hit by the Boar is flung 30' in a random direction and knocked prone. The Boar takes only half damage from non-magical weapons.
HD:10 AC:17 Atk:+7 Dmg:2d8 Shk:4/15 Mv:40’ ML:11 Skl:+1 Save:10+